SAN FRANCISCO (KTVU) - San Francisco Mayor Ed Lee is expressing his frustration with the National Park Service's decision to approve a final permit for the Patriot Prayer rally in Crissy Field.

The city is worried about a potential outbreak of violence in the wake of a deadly protest in Charlottesville, Virginia, where white supremacists clashed with counter-protesters.

Mayor Ed Lee said he's disappointed that NPS granted the final permit because even though the event is on federal land, it's San Francisco that will end up footing the bill for extra security.

"God pray, nobody gets hurt," Lee, flanked by San Francisco Police Chief Bill Scott and Supervisor President London Breed, told a crowd or reporters at City Hall about a half hour after the NPS made its announcement.

"These people, with hate-filled messages are coming into our city to wreak havoc," warned Lee.

"We will not let this rally tear us apart," said Breed. "They are not welcomed here because we know the spirit by which they bring to our city and we will drown them out again with the spirit of love."

"I ask our public and our residents of SF Bay Area to to honor our request to not dignify people who are coming in here under the guise of patriot and prayer words," said Lee, who has asked the public to not attend the 2 p.m. rally at Crissy Field this Saturday, August 26.

"No guns will be allowed for this event within the permitted areas," said Chief Scott.

The National Park Service has issued 26 permit conditions including; no firearms, ammunition, sticks, drones, helmets, large backpacks, animals, bicycles or anything that might be used as a weapon.

"By the way, it's on our dime," quipped Lee, who is upset that San Francisco will be coughing up the money to pay for added SFPD officers, even though the event is on federal land.

Some have criticized city leaders, saying they shouldn't try to squelch free speech, but they've fired back, saying that Patriot Prayer has staged similar rallies across the U.S, which have attracted neo-Nazis and white supremacists.

"We will not let this rally destroy our city we are prepared to do whatever it takes to flip the script," said Breed. The city has planned a counter-rally at Civic Center Plaza on Friday and Saturday at noon.

Friday's rally will boast politicians, while Saturday's rally will have a more festive atmosphere complete with music, food and face painting. Bay Area Native Michael Franti and Spearhead will headline Saturday's concert.

Mason Street near Crissy Field will be closed for Saturday's event, so the Presidio Trust has ordered House of Air, Planet Granite, Roaring Mouse Cycles, USF School of Nursing and Health Professionals and Sports Basement to close.

In a statement on the park website, the service explained its reasoning:

"The National Park Service has a long and proud tradition of being the site of peaceful expressions of people’s views under the First Amendment to the US Constitution which guarantees everyone the right to gather together and express their opinions non-violently. We cannot deny a permit to anyone planning to exercise their First Amendment rights based on their political stance or beliefs. We can deny a permit application for public safety reasons if the event raises such significant public safety concerns that law enforcement cannot manage the event."